Attachment of a tray gripper of a tray sealing machine

ABSTRACT

A tray gripper may be attached to a gripper arm of a tray sealing machine. For this purpose, the tray gripper is moved to a pre-assembly position by hooking the tray gripper onto the gripper arm. In addition, an eccentric is operated for exerting a clamping force upon the tray gripper that is disposed in the pre-assembly position, so that an attachment structure of the tray gripper is tensioned against an abutment structure of the gripper arm.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims foreign priority benefits under 35 U.S.C. §119(a)-(d) to German patent application number DE 10 2019 206 384.5,filed May 3, 2019, which is incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to the detachable attachment of a traygripper to a packaging machine that is formed as a tray sealing machine.

BACKGROUND

An exemplary tray sealing machine is known from EP 3 138 778 A1. Thetray sealing machine comprises arranged consecutively in the directionof production a feed belt for packaging trays to be sealed, a sealingdevice for sealing the packaging trays, and a discharge belt for thesealed packaging trays. A gripper system is provided which relocates thetrays to be packaged from the feed belt into the sealing device andrelocates the sealed trays from the sealing device onto the dischargebelt. The gripper system comprises two gripper arms that are movable inand against the direction of production and which, regarding thedirection of production, are arranged on opposite sides of the trays.Two tray grippers are detachably attached on each of the gripper arms.Two respective tray grippers each provided on opposite sides of thetrays interact for relocating, trays from the feed belt into the sealingdevice, while the other two oppositely disposed tray grippers interactfor relocating sealed trays from the sealing device onto the dischargebelt. The tray grippers each comprise a first and a second holdingfixture, by way of which they are attachable and detachable in a keylessmanner on and from a coupling device of the respective gripper arm. Theholding fixtures each comprise two respective mounting bolts which aremounted at a fixed distance to each other on an adjustment plateattached in an adjustable manner to the tray gripper. The mounting boltsare received in U-shaped openings of the coupling device. For thispurpose, the mounting bolts have a reduced diameter at their centralportion which is provided in a precise fit for the U-shaped opening.After inserting the mounting bolts into the openings, a spring plate ofthe coupling device ensures a reliable connection of the tray gripper tothe coupling device in that the spring plate in part encloses a mountingbolt. For detaching, the spring plate must be manually pushed away fromthe mounting bolt so that the tray gripper may be removed.

Gripper systems are also known from practice in which only one traygripper is provided on each gripper arm and is responsible forrelocating the trays into the sealing device as well as relocating thesealed trays out of the sealing device.

For a high throughput of the tray sealing machine, it is desirable torelocate the trays as quickly as possible. However, this results in veryhigh forces acting upon the tray grippers when accelerating ordecelerating. This is particularly critical with tray grippers which areshaped to be particularly long in order to be able to simultaneouslyrelocate as many trays as possible. During operation, oscillations andvibrations of the tray grippers may arise, which may have a negativeeffect on the positioning accuracy and may cause faults.

SUMMARY

It is an object of the disclosure to provide a way of detachablyattaching a tray gripper to a gripper arm of a tray sealing machinewhich allows for simple and quick exchange of the tray gripper and/orallows for particularly stable attachment.

According to the disclosure, a method for detachably attaching a traygripper to a gripper arm of a tray sealing machine is provided. The traygripper is moved to a pre-assembly position by hooking the tray gripperonto the gripper arm. By operating an eccentric, a clamping force isexerted on the tray gripper that is disposed in the pre assemblyposition, so that an attachment structure of the tray gripper istensioned against an abutment structure of the gripper arm.

By using the eccentric, a high tensioning force may be obtained forstable and reliable attachment of the tray gripper. Since the attachmentstructure of the tray gripper is tensioned against an abutment structureof the gripper arm, the tray gripper may be tensioned to the gripper armin a well-defined position.

The eccentric is preferably adjusted between a receiving position and atensioning position. In the receiving position, the tray gripper may bemoved to the pre-assembly position. In the tensioning position, theattachment structure of the tray gripper is tensioned against theabutment. structure of the gripper arm. If the tray gripper is to beremoved, the eccentric may be adjusted from the tensioning position tothe receiving position, so that the attachment structure of the traygripper is released.

The eccentric is preferably operated by operating a lever connected toan axis of the eccentric. Due to the lever effect, it is then easy toapply sufficiently high tensioning force. In the receiving position ofthe eccentric, the lever preferably projects away from the gripper armand in the tensioning position of the eccentric bears against thegripper arm. This ensures that the lever does not represent an obstacleduring operation of the tray sealing machine when the tray gripper ismounted. In addition, bearing against the gripper arm in the tensioningposition may give a feedback about a correct tensioning of the traygripper.

According to an easy-to-implement embodiment, the force upon the traygripper by the eccentric is exerted directly by way of contact betweenthe eccentric and the tray gripper. When tensioning the tray gripperagainst the abutment structure of the gripper arm, the eccentric maycome into contact with the tray gripper and tension it directly againstthe abutment structure of the gripper arm.

Alternatively, the force by the eccentric upon the tray gripper may alsobe exerted indirectly via an intermediate element. This allows for theeccentric to be positioned and dimensioned more freely. In addition, theintermediate element may be designed and shaped for particularly goodforce transmission and/or a particularly good engagement with the traygripper.

The intermediate element may be mounted, for example, to be slidable ona body of the gripper arm. With the mounting, a slide path of theintermediate element for tensioning the gripper arm may be specified.

The intermediate element preferably comprises a receiving structure,which receives the attachment structure of the tray gripper. In such anembodiment, particularly good force transmission between theintermediate element and the tray gripper is given. The receivingstructure preferably receives the attachment structure of the traygripper already in the pre-assembly position.

In order to obtain an increased tensioning force, at least one region ofthe intermediate element may be elastically deformed by the eccentric.In particular, the region of the intermediate element may be elasticallydeformed when the eccentric is operated for exerting the tensioningforce, in particular when adjusting the eccentric to the tensioningposition.

For a particularly vibration-resistant and defined attachment of thetray gripper, a line contact between the attachment structure and thegripper arm may be present when the attachment structure of the traygripper is tensioned against the abutment structure of the gripper arm.Preferably, there are even several line contacts present between theattachment structure and the gripper arm, in particular at least two, atleast three or at least four line contacts.

The eccentric may provide a tensioning force in the order of magnitudeof, for example, 20 kN. In particular, the tensioning force may be atleast 10 kN, at least 15 kN or at least 20 kN.

The disclosure also relates to a tray sealing machine. The tray sealingmachine is suitable, adapted, and configured to perform the methodaccording to the disclosure. Features described with regard to themethod may be transferred to the tray sealing machine and vice versa.

A tray sealing machine according to the disclosure comprises a sealingdevice for sealing trays and a gripper system for introducing the traysinto the sealing device. The gripper system is preferably alsoconfigured to remove the sealed trays from the sealing device. Thegripper system comprises a gripper arm and a tray gripper for grippingthe trays that is detachably attachable to the gripper arm. Preferably,two gripper arms are provided, on each of which at least one traygripper for gripping the trays may be attached in a detachable manner.

The gripper arm comprises an eccentric which is operable to be adjustedbetween a receiving position and a tensioning position. In the receivingposition of the eccentric, the tray gripper may be made to assume apre-assembly position by hooking the tray gripper onto the gripper arm.The eccentric is configured to be adjusted to the tensioning positionwhen the tray gripper is in the pre-assembly position. The eccentricthereby exerts a force upon the tray gripper, so that an attachmentstructure of the tray gripper is tensioned against an abutment structureof the gripper arm.

The gripper arm preferably also comprises a lever for operating theeccentric connected to an axis of the eccentric. In the receivingposition of the eccentric, the lever preferably projects away from thegripper arm and in the tensioning position of the eccentric, the leverbears against the gripper arm.

According to an embodiment, an intermediate clement is mounted to beslidable on a body of the gripper arm. The force upon the tray gripperwhen adjusting the eccentric to the tensioning position is exertedindirectly via the intermediate element.

The intermediate element may comprise a receiving structure whichreceives the attachment structure of the tray gripper. The receivingstructure is preferably formed to be hook-shaped. This allows forparticularly simple but also reliable reception of the attachmentstructure of the tray gripper and enables improved force transfer to thetray gripper.

In order to apply increased tensioning force for attaching the traygripper, the intermediate element may comprise a region that iselastically deformable by the eccentric when the eccentric is adjustedto the tensioning position.

The abutment structure of the gripper arm may form a support for a linecontact with the attachment structure of the tray gripper. The abutmentstructure of the gripper arm preferably even forms a support for morethan one line contact with the attachment structure, for example, for atleast two, at least three or at least four line contacts with theattachment structure.

The gripper arm preferably extends from the tray gripper upwardly.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, embodiments according to the disclosure are explainedin more detail with reference to the attached figures, where:

FIG. 1 shows a schematic perspective view of a tray sealing machineaccording to an embodiment;

FIG. 2 shows a schematic perspective view of the gripper system of thetray sealing machine according to the embodiment;

FIG. 3 shows a view of the gripper system from FIG. 2 in the viewingdirection along the direction of production upon insertion of a traygripper into the pre-assembly position according to an embodiment;

FIG. 4 shows a detailed view of section A from FIG. 3;

FIG. 5 shows the detailed view from FIG. 4 after the tray gripper hasbeen inserted into the pre-assembly position;

FIG. 6 shows the detailed view from FIGS. 4 and 5 after the tray gripperhas been tensioned onto the gripper arm;

FIG. 7 shows a schematic detailed view for illustrating the abutmentstructure of the gripper arm according to an embodiment;

FIG. 8 shows a schematic view of the attachment of the tray gripper tothe gripper arm according to an alternative embodiment; and

FIG. 9 shows a schematic representation of the attachment of the traygripper to the gripper arm according to a further alternativeembodiment.

DETAILED DESCRIPTION

FIG. 1 shows a tray sealing machine 1 according to an embodiment.Arranged consecutively along a direction of production P, tray sealingmachine 1 comprises a feed device 3 embodied as a feed belt forpackaging trays to be sealed, a sealing device 5 for sealing thepackaging trays, and a discharge device 7 embodied as a discharge beltfor sealed packaging trays. Sealing device 5 seals the packaging traysby sealing a top film on, which is withdrawn from a stock roll that isreceived on a film holder 9. For sealing the top film on, sealing device5 comprises a sealing tool upper part 11 and a sealing tool lower part13 which are movable along a vertical direction relative toward eachother to seal between themselves the top film to the packaging trays.The sealing may be done, for example, subject to heat and/or pressure. Acutting device may also be integrated into sealing device 5 and cut thetop film during or after the sealing process, thereby separating thepackagings from the composite of the top film. A residual film latticeof the top film may be wound onto a residual film winding device 15.

Tray sealing machine 1 comprises a gripper system 17 for relocatingpackaging trays to be sealed from feed device 3 into sealing device 5.Gripper system 17 is shown individually in FIG. 2. Gripper system 17comprises a carriage 19 which is mounted on two guide rods 21 extendingparallel to the direction of production P to be slideable in and againstthe direction of production P by way of a drive 23. On both lateralsides with respect to the direction of production P, a gripper arm 25 isprovided on carriage 19. The gripper arms 25 extend down from carriage19. Respective tray grippers 27 are detachably attachable to gripperarms 25. In FIG. 2, a tray gripper 27 is attached to one of gripper arms25, while other gripper arm 25 is shown without tray gripper 27 toillustrate the attachment mechanism. Gripper arms 27 extendsubstantially parallel to the direction of production P. By pivoting thegripper arms 25 relative to each other about axes running parallel tothe direction of production P, the tray grippers 27 may be moved towardeach other and in this manner may receive trays disposed between them.Carriage 19 may subsequently move along the direction of production P,whereupon the trays may be placed at a different position by pivotinggripper arms 25 apart from each other.

In the embodiment shown, exactly one tray gripper 27 is attachable toeach gripper arm 25. Preferably, gripper system 17 may in one processstep relocate packaging trays to be sealed from feed device 3 intosealing device 5 and sealed packaging trays from sealing device 5 todischarge device 7. For this purpose, tray grippers 27 are formed to besufficiently long such that packaging trays present on feed device 3 andalready sealed packaging trays in sealing device 5 may simultaneously begripped. After gripping them, carriage 19 moves along the direction ofproduction P and then places the packaging trays to be sealed, that werereceived from feed device 3, into sealing device 5 and the sealedpackaging trays, that were received in sealing device 5, onto dischargedevice 7. However, it would also be conceivable to provide two (or morethan two) separate tray grippers 27 on each gripper arm 25, of which,for example, one is responsible for feeding the packaging trays to besealed into sealing device 5 and one for removing the sealed packagingtrays from sealing device 5.

Tray grippers 27 should be detachably attached to the gripper arms 25 toallow for an exchange of tray grippers 27, for example for retoolingtray sealing machine 1 to a different tray format. The attachment oftray grippers 27 on gripper arms 25 may be formed similarly for bothgripper arms 25 and is explained in the following first for anembodiment shown in FIGS. 2 to 7. FIG. 3 shows gripper system 17 in theviewing direction along the direction of production P. Gripper system 17comprises a lever 29 at each of gripper arms 25 which is movable betweena receiving position and a tensioning position for the tensioningattachment of tray gripper 27. In FIG. 3, lever 29 of left gripper arm25 is in the receiving position, whereas lever 29 of right gripper arm25 is in the tensioning position. In the receiving position, lever 29protrudes out from gripper arm 25. In the tensioning position, lever 29bears against gripper arm 25.

FIG. 4 shows a detailed view of detail A from FIG. 3. In the embodimentshown, an intermediate element 33 is mounted to be movable on a body 31of gripper arm 25. In particular, intermediate element 33 is mounted onbody 31 for a motion in a horizontal plane along a direction V disposedperpendicular to the direction of production P. Intermediate element 33in the illustrated embodiment has two hook-shaped receiving structures35 and an end plate 39 connected to receiving structures 35. If lever 29is in the receiving position, as shown in FIG. 4, a reset element 41 oflever 29 engages with end plate 39 of intermediate element 33 and inFIG. 4 slides it in the sliding direction V to the right, so thatattachment structures 43 of tray gripper 27 formed as rods extendingparallel to the direction of production P may be inserted intohook-shaped receiving structures 35 of intermediate element 33. FIG. 5shows the arrangement in a pre-assembly position after insertion ofattachment structures 43 of tray gripper 27 into receiving structures 35of intermediate element 33 mounted to be slidable on body 31 of gripperarm 25. In the pre-assembly position, tray gripper 27 is already heldindependently on gripper arm 25 and need no longer be held by anoperator during the further steps of tensioning tray gripper 27 ontogripper arm 25.

Lever 29 is connected to an axis 45 that extends parallel to thedirection of production P and is mounted to be rotatable on gripper arm25. Provided on axis 45 is also an eccentric 47 which is rotated whenaxis 45 is rotated by rotating lever 29. In the receiving position oflever 29 (FIGS. 4 and 5), eccentric 47 is also in a receiving position.In its receiving position, eccentric 47 exerts no force uponintermediate element 33.

In order to firmly lock gripper arm 25 hooked onto tray gripper 27 inthe pre-assembly position, lever 29 is pivoted from the receivingposition shown in FIG. 5 to a tensioning position shown in FIG. 6. Whilelever 29 in the receiving position projects away from gripper arm 25, inparticular vertically, lever 29 in the tensioning position bears againstgripper arm 25. When lever 29 is rotated to the tensioning position (inFIG. 5 clockwise), eccentric 47 is also rotated. With this rotation,eccentric 47 engages with end plate 39 of intermediate element 33,whereby intermediate element 33 in the representation of FIGS. 4 to 6 ismoved in the sliding direction V to the left during this motion, traygripper 27 is entrained. Attachment structures 43 of tray gripper 27 aremoved toward body 31 of gripper arm 25 and finally tensioned against anabutment structure 49 of gripper arm 25. In FIG. 7, an abutmentstructure 49 for attachment structure 43 of tray gripper 27 is shown byway of example. Abutment structure 49 comprises a substantially V-shapednotch in body 31 of gripper arm 25 which extends parallel to thedirection of production P. When attachment structure 43 of tray gripper27 is tensioned against abutment structure 49 of gripper arm 25 due tothe tensioning force exerted by eccentric 47 via intermediate element 33upon attachment structure 43 of tray gripper 27, rod-shaped attachmentstructure 43 comes into contact with the notch along two lines. Due tothese line contacts parallel to the direction of production P, traygripper 27 may be attached in a particularly stable manner. Inparticular, tray gripper 27 is well stabilized against vibrations. Sincetwo attachment structures 43 are present in the embodiment shown forevery tray gripper 27 and are each tensioned against an abutmentstructure 49 of gripper arm 25, there are a total of four line contactsgiven between tray gripper 27 and gripper arm 25. Although the variantshown with two superimposed attachment structures 43 of tray gripper 27provides a particularly stable attachment, it would be conceivable inprinciple to provide only one attachment structure 43 for every traygripper 27. Of course, more than two attachment structures 43 may alsobe provided. As shown in FIG. 7, abutment elements 51 in the form ofrods made of steel may be provided in the notch in body 31 of gripperarm 25 and provide the contact surfaces to attachment structure 43 oftray gripper 27.

In order to be able to tension attachment structure 43 with aparticularly high tensioning force against abutment structure 49 ofgripper arm 25, eccentric 47 in the tensioning position may elasticallydeform rear plate 39 of the intermediate element.

If tray gripper 27 is to be removed again, lever 29 is pivoted from thetensioning position back to the receiving position. Eccentric 47 then nolonger exerts tensioning, force and tray gripper 27 may again beremoved. In the embodiment shown, a reset element 41 is provided onlever 29 which engages with end plate 39 of intermediate element 33 whenlever 29 is moved to the receiving position and again slidesintermediate element 33 such that tray gripper 27 may be easily removed(sliding in sliding direction V to the right in FIGS. 4 to 6). However,it would also be conceivable to manually slide intermediate element 33by pulling on tray gripper 27 when the tensioning force by eccentric 47is no longer present.

FIG. 8 shows an alternative embodiment of the tensioning connectionbetween gripper arm 25 and tray gripper 27. In this embodiment,attachment structures 43 of tray gripper 27 are not formed as rodsextending parallel to the direction of production P, but as hookstructures. Lever 29 is again provided pivotable on gripper arm 25. Inaddition, two rods 55 are fixedly attached to gripper arm 25. Traygripper 27 may be hooked by way of hook-shaped attachment structures 43onto rods 55 of gripper arm 25 and thereby made to assume a pre-assemblyposition. Subsequently, lever 29 may be adjusted by pivoting clockwisefrom the receiving position shown in FIG. 8 to a tensioning position. Aneccentric 47 again rotates together with lever 29 and, when rotatinglever 29 to the tensioning position, is pressed against an engagementregion 57 of tray gripper 27 and thereby moves tray gripper 27 away fromgripper arm 25. Hook-shaped attachment structures 43 of tray gripper 27are thus pressed against rods 55 of gripper arm 25, which in this caseform the abutment structure 49 of gripper arm 25. For releasing theattachment, lever 29 may be rotated from the tensioning position againcounterclockwise to the release position, whereupon tray gripper 27 maybe removed. In the embodiment according to FIG. 8, eccentric 47 engagesdirectly with tray gripper 27 and no intermediate element 33 isprovided.

FIG. 9 shows a further embodiment of the connection between tray gripper27 and gripper am 25 in which eccentric 47 engages without intermediateelement 33 directly with tray gripper 27. Similar to the embodiment ofFIGS. 2 to 7, attachment structure 43 of tray gripper 27 is in thisembodiment formed by a rod extending parallel to the direction ofproduction P. A hook 58 is provided on gripper arm 25. In addition, alever 29 that may be rotated between a receiving position and atensioning position is again provided with an eccentric 47 on gripperarm 25. In the receiving position of lever 29 and eccentric 47 shown inFIG. 9, tray gripper 27 may be hooked in a pre-assembly position ontogripper arm 25 by hooking attachment structure 43 into hook 58 ofgripper arm 25. From this pie-assembly position, lever 29 may be rotatedclockwise. Eccentric 47 is thereby rotated to a tensioning position,where it engages with attachment structure 43 of tray gripper 27 andpushes the latter in the direction away from gripper arm 25. Attachmentstructure 43 of tray gripper 27 is thereby tensioned against an abutmentstructure 49 formed by hook 58 whereby gripper arm 27 is locked. Ifgripper arm 27 is to be removed again, lever 29 may again be rotatedcounterclockwise to the receiving position, whereby the tensioning forceby eccentric 43 is cancelled.

What is claimed is:
 1. A method for detachably attaching a tray gripperto a gripper arm of a tray sealing machine, comprising: moving the traygripper into a pre-assembly position by hooking the tray gripper ontothe gripper arm; and operating an eccentric for exerting a clampingforce upon the tray gripper that is disposed in the pre-assemblyposition, so that an attachment structure of the tray gripper istensioned against an abutment structure of the gripper arm.
 2. Themethod according to claim 1, wherein operating the eccentric causesadjustment of the eccentric between a receiving position, in which thetray gripper is configured to be moved to the pre-assembly position, anda tensioning position, in which the attachment structure of the traygripper is tensioned against the abutment structure of the gripper arm.3. The method according to claim 2, wherein operating eccentriccomprises operating a lever that is connected to an axis of theeccentric, wherein the lever in the receiving position of the eccentricprojects away from the gripper arm and in the tensioning position of theeccentric bears against the gripper arm.
 4. The method according toclaim 1, wherein the force upon the tray gripper by the eccentric isexerted indirectly via an intermediate element.
 5. The method accordingto claim 4, wherein the intermediate element is mounted to be slidableon a body of the gripper arm.
 6. The method according to claim 4,wherein the intermediate element comprises a receiving structure whichreceives the attachment structure of the tray gripper.
 7. The methodaccording to claim 4, wherein at least one region of the intermediateelement is elastically deformed by the eccentric.
 8. The methodaccording to claim 1, wherein the force upon the tray gripper by theeccentric is exerted directly by contact between the eccentric and thetray gripper.
 9. The method according to claim 1, wherein a line contactbetween the attachment structure and the gripper arm is present when theattachment structure of the tray gripper is tensioned against theabutment structure of the gripper arm.
 10. A tray sealing machine with asealing device for sealing trays and a gripper system for introducingthe trays into the sealing device, the gripper system comprising; agripper arm; and a tray gripper detachably attachable to the gripper armfor gripping the trays; wherein the gripper arm comprises an eccentricwhich is operable to be adjusted between a receiving position and atensioning position; in the receiving position of the eccentric, thetray gripper is configured to be brought into a pre-assembly position byhooking the tray gripper onto the gripper arm; and the eccentric isconfigured to be adjusted to the tensioning position when the traygripper is in the pre-assembly position and to thereby exert a forceupon the tray gripper so that an attachment structure of the traygripper is tensioned against an abutment structure of the gripper arm.11. The tray sealing machine according to claim 10, wherein the gripperarm further comprises a lever that is connected to an axis of theeccentric for operating the eccentric, wherein the lever in thereceiving position of the eccentric projects away from the gripper armand in the tensioning position of the eccentric bears against thegripper arm.
 12. The tray sealing machine according to claim 10, furthercomprising an intermediate element mounted to be slidable on a body ofthe gripper arm, wherein the force upon the tray gripper when adjustingthe eccentric to the tensioning position is exerted indirectly via theintermediate element.
 13. The tray sealing machine according to claim12, wherein the intermediate element comprises a receiving structurethat is configured to receive the attachment structure of the traygripper.
 14. The tray ceiling machine according to claim 13, wherein thereceiving structure is hook-shaped.
 15. The tray sealing machineaccording to claim 12, wherein the intermediate element comprises aregion that is elastically deformable by the eccentric when theeccentric is adjusted to the tensioning position.
 16. The tray sealingmachine according to claim 10, wherein the abutment structure of thegripper arm forms a support for a line contact with the attachmentstructure of the tray gripper.
 17. A method for detachably attaching atray gripper to a gripper arm of a tray sealing machine, the methodcomprising: moving the tray gripper into a pre-assembly position byhooking the tray gripper onto the gripper arm; and operating aneccentric for exerting a clamping force upon the tray gripper that isdisposed in the pre-assembly position, so that an attachment structureof the tray gripper is urged against an abutment structure of thegripper arm.